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United States Patent |
6,095,923
|
Kageyama
|
August 1, 2000
|
Propeller shaft
Abstract
A propeller shaft comprises two torque transmission members, a viscous
fluid damper and a torsion bar which are arranged in parallel between the
torque transmission members, and a stopper for restricting the maximum
torsion angle of the torsion bar. Thus, torsional vibration characteristic
is adjusted in a wide range. Accordingly, a vibration a and noise in a
power transmission system can be prevented, and also, a starting
acceleration performance of a vehicle can be improved.
Inventors:
|
Kageyama; Hayashi (Tochigi, JP)
|
Assignee:
|
Viscodrive Japan Ltd. ()
|
Appl. No.:
|
064940 |
Filed:
|
April 22, 1998 |
Foreign Application Priority Data
Current U.S. Class: |
464/24; 464/97 |
Intern'l Class: |
F16D 003/80 |
Field of Search: |
464/24,97,113,160,182
192/56.3
|
References Cited
U.S. Patent Documents
2738660 | Mar., 1956 | Gail | 464/24.
|
3020775 | Feb., 1962 | Musser | 464/97.
|
3062023 | Nov., 1962 | Stolworthy | 464/97.
|
3350900 | Nov., 1967 | Harrison | 464/24.
|
3890803 | Jun., 1975 | Neal et al. | 464/97.
|
4048872 | Sep., 1977 | Webb | 464/24.
|
4082139 | Apr., 1978 | Davis | 464/24.
|
4365686 | Dec., 1982 | Orain | 464/113.
|
4774847 | Oct., 1988 | Breitweg | 464/97.
|
5310382 | May., 1994 | Guimbrtiere | 464/24.
|
5330038 | Jul., 1994 | Haaka | 464/24.
|
Foreign Patent Documents |
2631399 | Nov., 1989 | FR | 464/97.
|
Primary Examiner: Melius; Terry Lee
Assistant Examiner: Binda; Greg
Attorney, Agent or Firm: Graham & James LLP
Claims
What is claimed is:
1. A propeller shaft for torque transmission, comprising:
first and second torque transmission members in opposition to each other;
a torsion bar connecting the first torque transmission member and the
second torque transmission member, the torsion bar rotating integrally
with the first and second torque transmission members so as to perform a
function of torque transmission;
a viscous fluid damper including first and second relative rotation members
and a viscous fluid, the first and second relative rotation members being
individually connected to the first and second torque transmission
members, respectively, the first relative rotation member rotating
integrally with the first torque transmission member, the second relative
rotation member rotating integrally with the second torque transmission
member, with a viscous fluid between the relative rotation members to
transmit force parallel to the torsion bar, so that a shearing stress of
the viscous fluid generated between the relative rotation members absorbs
a vibration in a rotating direction when the torsion bar is twisted and
the relative rotation members make a relative rotation; and
a stopper for restricting a maximum torsion angle of the torsion bar,
wherein the stopper has a first abutting portion on the first torque
transmission member and a second abutting portion on the second relative
rotation member, with the abutting portions abutted against each other to
prevent the torsion bar from being further twisted when the torsion bar is
twisted at the maximum torsion angle.
2. The propeller shaft according to claim 1, wherein the viscous fluid
damper absorbs the relative rotation so as to perform a function of torque
transmission when the torsion bar is twisted and the relative rotation
members make the relative rotation.
3. The propeller shaft according to claim 1, wherein the first abutting
portion is located on an outer surface of the first torque transmission
member, and the second abutting portion is located on an outer surface of
the second relative rotation member.
4. The propeller shaft according to claim 1, wherein the torsion bar is
detachably connected to the first torque transmission member and to the
second torque transmission member.
5. The propeller shaft according to claim 4, wherein the torsion bar
engages with the first torque transmission member and the second torque
transmission member so that the torsion bar is prevented from relative
rotating with respect to the first and second torque transmission members.
6. The propeller shaft according to claim 1, wherein
the viscous fluid damper includes a pressure chamber, a plurality of
disk-like first resistance members in the pressure chamber, and a
plurality of disk-like second resistance members in the pressure chamber,
the pressure chamber is formed between the first and second relative
rotation members,
the viscous fluid is encapsulated in the pressure chamber,
the first resistance member engages with the first relative rotation member
so as to rotate integrally with the first relative rotation member,
the second resistance member engages with the second relative rotation
member so as to rotate integrally with the second relative rotation
member,
the first and second resistance members are arranged so as to alternately
overlap each other, and
the first and second resistance members generate the shearing stress of the
viscous fluid when the torsion bar is twisted and the relative rotation
members make the relative rotation.
7. The propeller shaft according to claim 6, wherein
the first and second resistance members alternately overlap each other
along an axial direction.
8. The propeller shaft according to claim 6, wherein
the first and second resistance members alternately overlap each other
along a direction intersecting a rotation axis of the torsion bar.
9. The propeller shaft according to claim 1, further comprising a vibration
stopper member arranged on an outer circumference of the torsion bar.
10. The propeller shaft according to claim 1, wherein
the first relative rotation member has a shaft shape, and is fixed to the
first torque transmission member,
the second relative rotation member has a cylindrical shape covering an
outer periphery of the first relative rotation member,
the torsion bar connects the first relative rotation member to the second
torque transmission member, and
the viscous fluid damper and the torsion bar are lined up along a rotation
axis of the torsion bar.
11. The propeller shaft according to claim 1, wherein the first relative
rotation member has a cylindrical shape, and is fixed to the first torque
transmission member,
the second relative rotation member has a cylindrical shape covering an
outer periphery of the first relative rotation member, and
the torsion bar penetrates through the first relative rotation member.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a propeller shaft which is arranged in a
power train (drive line) of a vehicle, and in particular, to a propeller
shaft which can adjust a torsional resonance point or the like.
In general, a great vibration and a noise are generated and made in the
case where torsional vibration characteristic of a propeller shaft of a
vehicle is improper and a torsional resonance point of the power train and
a normally rotational speed of the propeller shaft are coincident.
If a torsional rigidity of the propeller shaft is too high, it is hard to
make a connection (conjunction) of a clutch between an engine and a
transmission; for this reason, a starting acceleration performance of a
vehicle lowers. Further, when the vehicle is in an inertia running state,
a torque is not applied to the propeller shaft; for this reason, a
so-called lash noise (resulting from rattling and contact of gears) is
made at a portion where gears engage with each other.
In order to solve these problems as described above, there is a need of
absorbing a torsional vibration of the propeller shaft and lowering a
torsional rigidity so as to adjust torsional vibration characteristic.
In this related art, there are a double structure special shaft, and a
torque variation absorbing fly-wheel disclosed in Japanese Unexamined
Utility Model Publication No. 59-108848, etc.
The aforesaid double structure special shaft has an outer steel pipe and an
inner steel pipe penetrating through the outer steel pipe. These steel
pipes are connected to each other by means of rubber. Further, one and
another sides of respective outer and inner steel pipes are individually
connected with a coupling joint. In the special shaft, a torsional
rigidity is lowered by the flexibility of rubber, so that torsional
vibration characteristic can be improved.
Moreover, the aforesaid torque variation absorbing fly-wheel is called as a
double mass fly-wheel. The double mass fly-wheel is composed of a pair of
fly-wheels, a coil spring for connecting fly-wheels to each other, and the
like. In the torque variation absorbing fly-wheel, the torsional rigidity
is lowered by the flexibility of the coil spring and the inertia of both
fly-wheels, so that torsional vibration characteristic can be improved.
However, in the case of the special shaft, the torsional vibration
characteristic is limited depending upon a flexible rate determined by a
property of rubber and a thickness thereof; for this reason, it is
impossible to make a torsional angle great. Thus, a range of adjusting the
torsional vibration characteristic is narrow.
In the case of the torque variation absorbing fly-wheel, the range of
adjusting the torsional vibration characteristic is narrow like the case
of the special shaft, and further, the structure is complicated; for this
reason, the cost is high.
Neither special shaft nor torque variation absorbing fly-wheel has a
function of obtaining a desired torsional vibration characteristic.
For these reasons, neither special shaft nor the torque variation absorbing
fly-wheel can sufficiently solve the aforesaid problems relative to the
propeller shaft.
SUMMARY OF THE INVENTION
In accordance with the teachings of this invention, a propeller shaft is
provided that can adjust the torsional vibration characteristic within a
wide range, prevent a vibration and noise from being made in a power
train, and improve starting acceleration performance of a vehicle.
The propeller shaft includes two torque transmission members, a viscous
fluid damper and a torsion bar that are arranged in parallel between the
torque transmission members, and a stopper for restricting the maximum
torsion angle of the torsion bar.
In the propeller shaft, as a torque transmitted between the two torque
transmission members gradually increases, the torsion angle of the torsion
bar also increases. When the torsion angle of the torsion bar becomes
greater than a predetermined value (the maximum torsion angle), the
stopper is actuated so as to restrict the torsion of the torsion bar. The
torque increased after stopper actuation is then transmitted via the
stopper. The torsion of the torsion bar is restricted by means of the
stopper, so that the torsion bar is protected.
Before the stopper is actuated, in the case where the torque increases and
decreases and a first and second relative rotation members make a relative
rotation, vibration is absorbed by both viscosity of the viscous fluid of
the viscous fluid damper, and torsion of the torsion bar. More
specifically, the rigidity of the propeller shaft is properly reduced by
the torsion bar, and a fine vibration in a rotating direction is
effectively absorbed by the viscous fluid damper.
As described above, two kinds of damper mechanisms (a viscous fluid damper
and a torsion bar) having different characteristics are arranged in
parallel between the two torque transmission members. Thus,
characteristics by both damper mechanisms are independently developed or
mutually compensated, allowing a wide range for adjusting torsional
vibration characteristics. Therefore, by setting a torsional resonance
point of a power train of a vehicle lower than a normally rotational speed
of the propeller shaft, vibration and noise can be effectively prevented.
Further, the torsional rigidity of the propeller shaft is lowered, so that
connection of a clutch is easily made, thus improving starting
acceleration performance. Moreover, when the vehicle is in an inertial
running state, even if the torque is not applied to the propeller shaft,
it is possible to prevent lash noise in the gear engaging portion.
The propeller shaft of the present invention is constructed as a unit with
the viscous fluid damper and the torsion bar incorporated therein so that
assembling, removal, replacement, and the like are readily performed. By
applying the viscous fluid damper to the propeller shaft, the viscous
fluid damper has a wide range of uses and a cost reduction of the viscous
fluid damper itself is achieved.
A more complete understanding of the propeller shaft will be afforded to
those skilled in the art, as well as a realization of additional
advantages and objects thereof, by a consideration of the following
detailed description of the preferred embodiment. Reference will be made
to the appended sheets of drawings which will first be described briefly.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view showing a propeller shaft according to a
first embodiment of the present invention;
FIG. 2 is a cross sectional view of one-side torque transmission member
used in each embodiment;
FIG. 3 is a view viewed from an arrow III of FIG. 1;
FIG. 4 is a graph showing characteristics in the case where different
torsion bars are used in each embodiment;
FIG. 5 is a cross-sectional view showing a propeller shaft according to a
second embodiment; and
FIG. 6 is a cross-sectional view showing a stopper of a torsion bar
different from each embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments according to the present invention will be described below with
reference to the accompanying drawings.
A first embodiment of the present invention will be described with
reference to FIG. 1 to FIG. 4. FIG. 1 shows a propeller shaft 1 according
to this first embodiment. In these figures, members, to which no reference
numeral is given, are omitted in their illustration.
As shown in FIG. 1, a propeller shaft 1 comprises a one-side torque
transmission member (first torque transmission member) 3, another-side
torque transmission member (second torque transmission member) 5, a
viscous fluid damper 7, a torsion bar 9, a stopper 11, a cylindrical
member 13, a vibration stopper member 15, and the like.
The viscous fluid damper 7 has a cylindrical housing 17 (second relative
rotating member), a shaft member (first relative rotating member) 19
arranged in the center of the cylindrical housing 17, a viscous fluid, a
pressure chamber 21, a plurality of disk-like outer plates (second
resistance member) 23, and a plurality of disk-like inner plates (first
resistance member) 25.
The pressure chamber 21 is formed between the cylindrical housing 17 and
the shaft member 19. A viscous fluid is encapsulated in the pressure
chamber 21.
The outer and inner plates 23 and 25 are arranged in the pressure chamber
21 so as to alternately overlap each other along a rotary shaft direction
(the shaft member 19 direction, hereinafter, referred to as axial
direction). An inner circumferential surface of the housing 17 is formed
with a plurality of grooves 24 along the axial direction. The outer plates
23 respectively fitted into these grooves 24, and are arranged so as to be
movable along the axial direction. An outer circumferential surface of the
shaft member 19 is formed with a plurality of grooves 26 along the axial
direction. The inner plates 25 respectively are fitted into these grooves
26, and are arranged so as to be movable along the axial direction.
X-rings 27 and 29 (seal having an X-shaped cross section) are arranged on
opposite ends of the pressure chamber 21 between the housing 17 and the
shaft member 19. These X-rings 27 and 29 permit a relative rotation of the
housing 17 and the shaft member 19, and prevent a leakage of viscous fluid
from the pressure chamber 21.
As shown in FIG. 2 and FIG. 3, one-side torque transmission member 3 is
formed into a substantially U-letter shape, and has a proximal portion 31
and two arms 33,33 projecting from both ends of the proximal portion 31.
The proximal portion 31 is fixed on one end face of the shaft member 19 of
the viscous fluid damper 7. These arms 33 are individually formed with a
hole 35 for making a connection with a mating side shaft member of a power
transmission system of a vehicle.
As shown in FIG. 1, another-side torque transmission member 5 is formed
into a substantially U-letter shape, and has a proximal portion 37 and two
arms 39,39 projecting from both ends of the proximal portion 37. These
arms 39 are individually formed with a hole 41 for making a connection
with a mating side shaft member of the power transmission system of the
vehicle.
The torsion bar 9 is composed of connective portions 43 and 45 at its
opposite ends and a small-diameter portion 47 formed between these
connective portions. These connective portions 43 and 45 are formed with
spline portions 49 and 55 at their outer circumferential faces,
individually. The other end of the shaft member 19 of the viscous fluid
damper 7 is formed with an engaging hole 44 having a spline-shaped inner
circumferential surface. When one-side connective portion 43 is inserted
into the engaging hole 44 of the shaft member 19, the spline portion 49
engages with the inner circumferential surface of the engaging hole 44, so
that the relative rotation of the shaft member and the torsion bar can be
prevented. In this state, a spring pin 51 is penetrated through one-side
connective portion 43 and the shaft member 19, so that one-side connective
portion 43 can be prevented from coming off from the engaging hole 44. On
the other hand, the proximal portion 37 of another-side torque
transmission member 5 is formed with an engaging hole 46 having a
spline-shaped inner circumferential surface. An end portion of
another-side connective portion 45 is provided with a screw portion 53.
When another-side connective portion 45 is inserted into the engaging hole
46 of another-side torque transmission member 5, the spline portion 55
engages with the inner circumferential surface of the engaging hole 46 so
that the relative rotation of the torsion bar and the torque transmission
member 5 can be prevented. In this state, a nut 57 is screwed into the
screw portion 53, so that another-side connective portion 45 can be
prevented from coming off from the engaging hole 46.
In the manner as described above, the torsion bar 9 is connected between
the spline portion 49;55 and the engaging holes 44;46 so as to be freely
attached and detached. Therefore, it is possible to easily perform a
replacement of other torsion bar having different characteristic.
The torsion bar 9 is attached to the cylindrical member 13 in the manner as
described above, and thereafter, the cylindrical member 13 is welded to
the housing 17 of the viscous fluid damper 7 and another-side torque
transmission member 5 to connect these members.
As described above, one-side torque transmission member 3 and another-side
torque transmission member 5 are connected by means of the torsion bar 9
and the viscous fluid damper 7 which are arranged in parallel.
An outer proximal portion of the vibration stopper member 15 is fixed onto
the inner surface of the cylindrical member 13. A slight gap 63 is defined
between a vibration stopper portion 61 and the small-diameter portion 47
of the torsion bar 9. This gap 63 permits a rotation of the torsion bar 9
(small-diameter portion 47), and serves to prevent the torsion bar 9 from
being vibrated.
As shown in FIG. 3, the stopper 11 is composed of four projecting portions
(second abutting portion) 65 on the outer surface of the cylindrical
housing 17 of the viscous fluid damper 7, and arms (first abutting
portion) 33 of one-side torque transmission member 3. These projecting
portion 65 and arm 33 abut against each other in their rotating direction,
and thereby, the maximum torsion angle of the torsion bar 9 is restricted.
As described above, the stopper 11 is arranged outside the propeller shaft
1.
When a torque transmitted between the torque transmission members 3 and 5
is smaller than a predetermined value and is constant, the torque is
transmitted through the shaft member 19 and the torsion bar 9.
When a torque transmitted between the torque transmission members 3 and 5
is smaller than a predetermined value and varies, the torsion angle of the
torsion bar 9 increases and decreases, and then, the housing 17 and the
shaft member 19 make a relative rotation. At this time, a shearing stress
is generated in the viscous fluid by the outer and inner plates 23 and 25.
Thus, the torque is transmitted through the shaft member 19 and the
torsion bar 9, and further, is transmitted through the shaft member 19,
the inner plate 25, the outer plate 23, the housing 17 and the cylindrical
member 13. In other words, the torque is transmitted by means of the
torsion bar 9 and the viscous fluid damper 7. Moreover, at this time,
vibration in rotating direction is absorbed by the viscosity of viscous
fluid between the housing 17 and the shaft member 49.
When the torque transmitted between the torque transmission members 3 and 5
becomes not less than a predetermined value and the torsion angle of the
torsion bar 9 becomes great, the arms 33 of one-side torque transmission
member 3 are abutted against the projecting portions 65 so as to actuate
the stopper 11. Thus, if the torque exceeds the predetermined value, the
torque is transmitted through the stopper 11, the housing 17 and the
cylindrical member 13.
As described above, when the torque is smaller than the predetermined value
and varies, the stopper is 11 not actuated, and vibration is absorbed by
both viscosity of the viscous fluid of the viscous fluid damper 7 and the
torsion of torsion bar 9. In particular, the rigidity of the propeller
shaft 1 is properly reduced by means of the torsion bar 9, and a fine
vibration in the rotating direction is effectively absorbed by means of
the viscous fluid damper 7.
Further, when the torque is not less than the predetermined value, the
stopper 11 is actuated, and the torsion angle of the torsion bar 9 is
restricted so that the torsion bar 9 is protected.
Curved lines 67, 69 and 71 shown in FIG. 4 show a transmission torque (T)
between the torque transmission members 3 and 5 and a torsion angle in the
propeller shaft 1.
As described above, the torsion bar 9 is replaceable, and the aforesaid
curved lines 67, 69 and 71 individually show characteristics in the case
where three kinds of torsion bars 9 having different small-diameter
portions 47 are used. The small-diameter portion 47 of the torsion bar 9
becomes gradually small in the order of the curved lines 67, 69 and 71.
As shown by these curved lines 67, 69 and 71, the greater the torsion angle
becomes, the more the transmission torque (T) increases. Further, as the
torsion angle gradually approaches the elastic limit of the torsion bar,
the transmission torque (T) suddenly rises up (increases). At this time,
the stopper 11 is actuated, and then, a torque transmission is performed
so that the torsion bar 9 is protected.
Thus, it is possible to vary characteristic of the propeller shaft 1 by
replacing the torsion bar 9.
The propeller shaft 1 thus constructed has the following effects.
In the propeller shaft 1, two kinds of damper mechanisms (viscous fluid
damper 7, torsion bar 9) having different characteristics are arranged in
parallel between the torque transmission members 3 and 5. Thus,
characteristics by both damper mechanisms are independently and
additionally developed, or are mutually compensated. As a result,
torsional vibration characteristics such as torsional rigidity and
vibration absorbing function are adjusted in a wide range.
Therefore, it is possible to set a torsional resonance point of a power
train of a vehicle lower than a normally rotational speed of the propeller
shaft 1, so that vibration and noise can be effectively prevented.
The torsional rigidity of the propeller shaft 1 is lowered, so that the
connection of clutch is easy to be made; therefore, a starting
acceleration performance can be improved. Further, when the vehicle is in
an inertial running state, even if the torque is not applied to the
propeller shaft 1, it is possible to prevent lash noise from being made in
the gear engaging portion.
The torsion bar 9 is replaceable, so that a desired characteristic can be
obtained by freely combining the viscous fluid damper 7 and various
torsion bars 9. As a result, torsional vibration characteristic can be
adjusted in a wide range.
Thus, the propeller shaft 1 is widely applicable to various vehicles, and a
reduction of cost can be achieved by mass production.
The vibration of the torsion bar 9 is prevented by means of the vibration
stopper member 15, so that the vibration of the propeller shaft 1 can be
further reduced. Further, by using the vibration stopper member 15,
vibration is prevented even if the torsion bar 9 is thin, so that a thin
torsion bar can be replaced. Therefore, a selective range of
characteristic can be further widened.
Even if the torsion bar 9 is formed thin, the torsion bar 9 is protected by
means of the stopper 11 from a excessive torsion.
Since the stopper 11 is arranged outside the propeller shaft 1, adjustment
is easy, more specifically, it is possible to actuate the stopper 11 at a
small torsion angle of the torsion bar 9 or to actuate the stopper 11 at a
large torsion angle thereof. Further, it is possible to readily adjust an
actuating torsion angle in accordance with the replaced torsion bar 9
having different characteristic.
One-side torque transmission member 3 is connected to another-side torque
transmission member 5 via the shaft member 19 of the viscous fluid damper
7 and the torsion bar 9. The viscous fluid damper 7 and the torsion bar 9
are functionally arranged in parallel, and are structurally arranged in
the axial direction. Moreover, the disk-like plates 23 and 25 of the
viscous fluid damper 7 are arranged in the axial direction.
For this reason, it is possible to make small a diameter of the propeller
shaft 1, and to make small an arrangement space in a diametrical
direction.
The propeller shaft 1 is constructed as a unit in a manner that viscous
fluid damper 7 and the torsion bar 9 are incorporated therein; therefore,
assembling, removal, replacement and the like are readily performed.
In the manner as described above, by applying the viscous fluid damper 7 to
the propeller shaft 1, the viscous fluid damper 7 is used for various
purposes, and a cost reduction of the viscous fluid damper 7 itself is
achieved.
When the torque increases and decreases before the stopper 11 is actuated
and the housing 17 and the shaft member 19 make a relative rotation, a
part of the torque transmitted by the torsion bar 9 is transmitted between
the housing 17 and the shaft member 19 via the viscous fluid.
For this reason, a part of a load onto the torsion bar 9 by a sudden
increase and decrease of torque is dispersed and absorbed in the viscous
fluid damper 7, so that the torsion bar 9 is further protected.
Also, not only the cylindrical member 13 and the housing 17 are connected
to each other by welding, but also they may be connected to each other by
means of a bolt 70 shown by a two-dotted chain line in FIG. 1. In this
case, workability for replacing the torsion bar 9 is improved as compared
with the case of welding.
Next, A second embodiment of the present invention will be described below
with reference to FIG. 5. FIG. 5 shows a propeller shaft 73 according to
this embodiment. In this figure, members, to which no reference numeral is
given, are omitted in their illustration. Also, in the explanation of this
second embodiment and in FIG. 5, like reference numerals are used to
designate the same functional member as the first embodiment, and a
repeated explanation for these functional members is omitted.
As shown in FIG. 5, the propeller shaft 73 comprises one-side torque
transmission member (first torque transmission member) 3, another-side
torque transmission member (second torque transmission member) 5, a
viscous fluid damper 75, a torsion bar 9, a stopper 77, a cylindrical
member 79 and the like.
A pressure chamber 85 is formed between a housing (second relative rotation
member) 81 of the viscous fluid damper 75 and a shaft member (first
relative rotation member) 83 arranged in the center thereof. A viscous
fluid is encapsulated in the pressure chamber 85.
In an interior of the pressure chamber 85, cylindrical plate groups (first
and second resistance members) 89 and 87 are arranged. These plate groups
87 and 89 comprise different-diameter cylindrical plates alternately
arranged in a diametrical direction.
The plate group 87 is fixed to the housing 81; on the other hand, the plate
group 89 is fixed to the shaft member 83 by means of an axial-direction
engaging portion 91 provided in each plate. The viscous fluid is prevented
from leaking from the pressure chamber 85 by means of X-rings 27 and 29
arranged between the housing 81 and the shaft member 83.
A proximal portion 31 of one-side torque transmission member 3 is fixed to
the shaft member 83 of the viscous fluid damper 75. The stopper 77 is
composed of four projecting portions 93 provided in the housing 81 of the
viscous fluid damper 75 and arms 33 of one-side torque transmission member
3, and is arranged outside the propeller shaft 73. These projecting
portions 93 and arms 33 are abutted against each other in their both
(normal and reverse) rotating direction, and thereby, the maximum torsion
angle of the torsion bar 9 is restricted.
One-side connective portion 43 of the torsion bar 9 is connected to the
shaft member 83 of the viscous fluid damper 75 via a spline portion 49,
and is prevented from coming off by means of a spring pin 51. On the other
hand, another-side connective portion 45 is connected to the another-side
torque transmission member 5 via a spline portion 55, and is prevented
from coming off by means of a nut 57 screwed into a screw portion 53.
As seen from the above explanation, the torsion bar 9 connected via the
spline portions 49 and 55 is removable (attachable and detachable), and is
replaceable with a torsion bar having different characteristic.
The torsion bar 9 is attached to the cylindrical member 79, and thereafter,
the cylindrical member 79 is welded to the housing 81 of the viscous fluid
damper 75 and another-side torque transmission member 5 to connect these
members.
In this manner, one-side torque transmission member 3 and another-side
torque transmission member 5 are connected to each other by means of the
torsion bar 9 and the viscous fluid damper 75 which are arranged in
parallel.
When a torque transmitted between the torque transmission members 3 and 5
is smaller than a predetermined value is constant, the torque is
transmitted through the shaft member 83 and the torsion bar 9.
When the torque is smaller than the predetermined value and varies, the
housing 81 and the shaft member 83 make a relative rotation, and then, a
shearing stress is generated in a viscous fluid by means of plate groups
87 and 89, respectively. Thus, the torque is transmitted via the shaft
member 83 and the torsion bar 9, and further, is transmitted between plate
groups 87 and 89. In other words, the torque is transmitted by means of
the torsion bar 9 and the viscous fluid damper 75. Further, at this time,
a vibration in a rotating direction is absorbed by the viscosity of
viscous fluid between the housing 81 and the shaft member 83. Thus, the
vibration is absorbed by two characteristics, that is, the viscosity of
viscous fluid of the viscous fluid damper 75 and the torsion of the
torsion bar 9. In particular, the rigidity of the propeller shaft 1 is
properly reduced by means of the torsion bar 9, and a fine vibration in a
rotating direction is effectively absorbed by means of the viscous fluid
damper 75.
When the torque becomes not less than the predetermined value and the
torsion angle of the torsion bar 9 becomes great, the arm 33 of one-side
torque transmission member 3 abuts against the projecting portion 93 to
actuate the stopper 77. Thus, the torque exceeding the predetermined value
is transmitted via the stopper 77, the housing 81 and the cylindrical
member 79. More specifically, the torsion angle of the torsion bar 9 is
restricted by means of the stopper 77, so that the torsion bar 9 can be
protected.
Like the curved lines 67, 69 and 71 of the propeller shaft 1 shown in FIG.
4, in the propeller shaft 73, the greater the torsion angle becomes, the
more the transmission torque (T) between the torque transmission members 3
and 5 increases. Further, when the torsion angle gradually approaches the
elastic limit of the torsion bar 9 and the transmission torque (T)
suddenly rises up (increases), the stopper 77 is actuated, so that the
torsion bar 9 is protected.
Thus, it is possible to greatly adjust characteristic of the propeller
shaft 73 by replacing the torsion bar 9 with a torsion bar having
different small-diametrical portion 47.
The propeller shaft 73 thus constructed has the following effects.
In the propeller shaft 73, two kinds of damper mechanisms (viscous fluid
damper 75, torsion bar 9) having different characteristics are arranged in
parallel. Thus, characteristics by both damper mechanisms are additionally
developed, or are mutually compensated. As a result, torsional vibration
characteristics are adjusted in a wide range.
Therefore, by setting a torsional resonance point of a power train of a
vehicle lower than a normally rotational speed of the propeller shaft 73,
vibration and noise can be effectively prevented.
The torsional rigidity of the propeller shaft 73 is lowered, so that the
connection of clutch is easy to be made; therefore, a starting
acceleration performance can be improved. Further, when the vehicle is in
an inertial running state, even in the case where the torque is not
applied to the propeller shaft 73, it is possible to prevent lash noise
from being made in the gear engaging portion.
The torsion bar 9 is replaceable, so that a desired characteristic can be
obtained by freely combining the viscous fluid damper 75 and various
torsion bars 9. As a result, torsional vibration characteristic can be
adjusted in a further wide range.
Thus, the propeller shaft 73 is widely applicable to various vehicles, and
a reduction of cost can be achieved.
Even if the torsion bar 9 is formed thin, the torsion bar 9 is protected by
means of the stopper 77 from a excessive torsion.
Since the stopper 77 is arranged outside the propeller shaft 73, adjustment
is easy; more specifically, it is possible to actuate the stopper 11 at a
small torsion angle of the torsion bar 9 or to actuate the stopper 77 at a
large torsion angle thereof. Further, it is possible to readily adjust the
torsion angle in accordance with the torsion bar 9 having different
characteristic.
The torque transmission members 3 and 5 are connected to each other via the
shaft member 83 of the viscous fluid damper 75 and the torsion bar 9. The
viscous fluid damper 75 and the torsion bar 9 are functionally arranged in
parallel, and are structurally arranged in the axial direction. Thus, the
propeller shaft has a small diameter, so that an arrangement space can be
made small in a diametrical direction.
In the viscous fluid damper 75, since the cylindrical plate groups 87 and
89 are arranged in the diametrical direction, sufficient vibration
absorbing function can be obtained even if the propeller shaft 73 is made
short in the axial direction. Therefore, the propeller shaft 73 is further
made short in the axial direction, so that an arrangement space in the
axial space can be made small.
The propeller shaft 73 is constructed as a unit in a manner that viscous
fluid damper 75 and the torsion bar 9 are incorporated therein; therefore,
assembling, removal, replacement and the like are readily performed.
By applying the viscous fluid damper 75 to the propeller shaft 73, the
viscous fluid damper 75 is used for various purposes, and a cost reduction
of the viscous fluid damper 75 itself is achieved.
Further, as shown in FIG. 6, the torsion bar 9 and the shaft members 19 and
83 may be prevented from coming off by means of a stopper ring 95.
Further, in place of shaft members 19 and 83 of the first and second
embodiments, by using a cylindrical shaft member, the torsion bar 9 may be
penetrated through a hollow portion of the shaft member. Whereby the
viscous fluid damper is arranged in line (parallel) with the torsion bar 9
along the diametrical direction.
With the aforesaid construction, the viscous fluid damper is arranged in
line with the torsion bar 9 along the diametrical direction, so that the
propeller shaft can be made short. Therefore, this is advantageous in the
case of arranging the propeller shaft in a narrow space.
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